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Biomedical subjects

R A Kaufman

Publications and source records attributed to R A Kaufman.

At least 73 records · Page 4Linked to original sources
PubMed1980

Congenitally absent thoracic pedicle in a child with rhabdomyosarcoma.

A case of congenital absence of a thoracic pedicle is reported in a 9 year old boy with embryonal rhabdomyosarcoma of the eyelid. In this clinical setting a surgical exploration was necessary in order to differentiate a developmental anomaly from an acquired metastatic deposit.

Child↗
PubMed1980

Recent advances in measurement of amylase activity--a comparative study.

We evaluated four kinetic amylase procedures with respect to kinetics, analytical range, blank rates, reagent stability, reagent impurities, interfering substances, and intrinsic sensitivities. Each of the methods is shown to have its own unique advantages and disadvantages. A preliminary discussion of some alternative methods, in which glycosidic p-nitrophenyl alpha-oligosaccharides are substrates, is included.

Amylases↗
PubMed1980

Ion effects in measurement of ionized calcium with a calcium-selective electrode.

We examined the performance characteristics of an improved electrode for measurement of ionized calcium (Orion Research, Inc.) with respect to interferences by Na+, K+, Li+, Mg2+, and H+, as well as the effect of changes in ionic strength and osmolality. At physiologically observed concentrations, all ions except Na+ insignificantly affected ionized-calcium measurements. The decrease in ionized Ca2+ with increased Na+ concentration is caused by the increase in ionic strength and the associated decrease in Ca2+ activity. Sodium had no significant direct effect in concentrations below 250 mmol/L. A previously published (Clin. Chem. 23: 690, 1977) equation for the Na+ correction is invalid for this improved electrode. Changes in osmotic pressure negligibly affect electrode response. Significant changes in ionic strength, as would be observed in severe hypo- and hypernatremic sera, increase or decrease, respectively, values for ionized calcium by changing Ca2+ activity. With aqueous Ca2+ solutions, changes of less than or equal to 3% were observed for Na+ concentrations that deviate from 140 mmol/L by not more than 20 mmol/L. Because the calcium ion activity is considered to be the physiologically important variable, we suggest that no correlation be made for ionic strength effects.

Calcium↗
PubMed1979

Preoperative diagnosis of splenic cysts in children by gray scale ultrasonography.

Ultrasonography is a useful noninvasive modality for the diagnosis of splenic cysts in children. Characteristic features plus the typical clinical and radiographic presentation should obviate the need for further more invasive and costly techniques which add little to diagnostic accuracy. Additional advantages offered by ultrasound a minimal patient discomfort, no ionizing radiation, and immediate reassurance to parents that the mass is a cyst. We report two cases of epidermoid splenic cysts preoperatively diagnosed by ultrasonography. The typical sonographic characteristics are presented and the sonographic differential diagnosis is discussed.

Adolescent↗
PubMed1978

False negative bone scans in neuroblastoma metastatic to the ends of long bones.

Studies of 12 children with neuroblastoma were performed to assess the comparative sensitivity of skeletal radiography and 99mTc pyrophosphate bone scintigraphy in the detection of metastases to the ends of long bones. A total of 18 lesions were detected in six patients. Fourteen were demonstrated only by radiography, whereas four were positive by both methods. In no case was a lesion detected by scintigraphy alone. Small lesion size, lytic radiographic appearance, metaphyseal location, and technical difficulties in imaging the knee all contribute to the high incidenmce of false negative scans. Lesions in two of the nine patients with metastatic disease to bone would have been missed on the basis of bone scans alone. Accordingly, the radiographic skeletal survey seems to remain a necessary part of the neuroblastoma workup.

Bone Neoplasms↗
PubMed1977

Biosynthesis of carnitine in Neurospora crassa.

In growing cultures of Neurospora crassa lysine auxotroph 33933, (a) beta-hydroxy-epsilon-N-trimethyllysine and gamma-N-trimethylaminobutyraldehyde, postulated precursors of carnitine in the rat, effectively blocked synthesis of labeles carnitine from epsilon-N-[CH3-3H]trimethyllysine; and (b) beta-hydroxy-epsilon-N[CH3-3H[trimethyllysine and gamma-N-[CH3-3H]trimethylaminobutyraldehyde were effectively utilized for carnitine formation. From these isotopic experiments, the latter steps of carnitine synthesis in Neurospora are postulated to be epsilon-N-trimethyllysine leads to beta-hydroxy-epsilon-N-trimethyllysine leads to gamma-N-trimethylaminobutyraldehyde leads to gamma-butyrobetaine leads to carnitine.

Carnitine↗
PubMed1976

Gastrointestinal perforation without intraperitoneal air-fluid level in neonatal pneumoperitoneum.

Twenty-one cases of neonatal pneumoperitoneum seen at the C.S. Mott Children's Hospital between 1970 and 1974 were reviewed. Of 14 cases with autopsy or surgically proven gastrointestinal perforation, six did not have an intraperitoneal air-fluid level on the initial cross-table lateral roentgenogram while eight did. Four cases of pneumoperitoneum secondary to mechanically assisted ventilation and air leak phenomenon had no air-fluid level. A postmortem study in one premature infant cadaver suggests that the air-fluid level may not be reliably demonstrated when the amount of intraperitoneal fluid is small. These data support the contention that an intraperitoneal air-fluid level does not uniformly occur in perforated viscus and that its absence, even in the presence of mechanically assisted ventilation, does not exclude the necessity for surgical intervention. In some cases, water-soluble contrast examination of the gastrointestinal tract appears to be a more reliable diagnostic adjunct to document a perforated viscus, when a definite intraperitoneal air-fluid level is not present.

Humans↗